Field of the Invention
The present disclosure relates to a lithography apparatus and a method of manufacturing an article.
Description of the Related Art
As a request for miniaturization of a semiconductor device, MEMS, or the like increases, in addition to a conventional photolithography technique, a microfabrication technique in which an imprint material on a substrate is molded by using a mold and a pattern of the imprint material is formed on the substrate is attracting attention. This technique is also referred to as an imprint technique, and enables to form a fine structure on the order of several nanometers on the substrate. An example of the imprint technique includes a photo-curing method. An imprint apparatus that employs the photo-curing method firstly applies a photo-curable imprint material to a shot region, which is an imprint region, on a substrate. Next, a pattern portion of a mold (original) is brought into contact with (impressed against) the imprint material while the pattern portion of the mold and the shot region are positioned, and the imprint material is filled in the pattern portion. Then, after the imprint material is cured by irradiation of light, the pattern portion of the mold and the imprint material are separated from each other, so that a pattern of the imprint material is formed in the shot region on the substrate.
In such an imprint apparatus, higher flatness of the substrate is required to form a fine structure on the substrate. When flatness of a holding surface of a substrate chuck that holds the substrate is reduced, however, the flatness of the substrate held by the substrate chuck may be reduced. The reduction in the flatness of the holding surface of the substrate chuck is caused by, for example, attachment of a foreign substance onto the holding surface of the substrate chuck.
Then, Japanese Patent Laid-Open No. 8-115868 discloses a technique of cleaning a holding surface of a substrate chuck. In a state where abrasive having high hardness and abrasive containing an organic material are brought into contact with a wafer chuck with a given pressure, such abrasive is caused to frictionally slide with the wafer chuck by a planetary gear method. Moreover, in Japanese Patent Laid-Open No. 9-283418, a cleaning plate in which a grid groove is cut is brought into contact with a wafer chuck in an appropriate pressurization condition to relatively move with the wafer chuck.
FIG. 16 is a cross-sectional view of a substrate chuck and a cleaning member. In a state where a polishing pad 161 which is arranged on a lower surface of the cleaning member and a substrate chuck 102 are brought into contact with each other, the polishing pad 161 or the substrate chuck 102 is moved, so that a foreign substance 360 attached to a surface (hereinafter, referred to as a holding surface) of the substrate chuck 102, on which a substrate is held, is able to be removed. On the holding surface of the substrate chuck 102, a plurality of protrusions are formed in order to make an area where the substrate chuck 102 contacts the substrate as small as possible so that no foreign substance is held between the substrate and the holding surface. Thus, particles 350 that are generated when the holding surface is cleaned may be attached to spaces between the plurality of protrusions. When the substrate chuck 102 moves, for example, the particles 350 attached to the spaces between the plurality of protrusions may drift in a space inside an imprint apparatus and be attached onto the substrate or to a pattern portion of a mold. The particles 350 attached onto the substrate or to the pattern portion of the mold may cause a defective pattern or breakage of the pattern portion.
In Japanese Patent Laid-Open No. 8-115868, a unit for cleaning is covered with a shielding cover and an exhaust duct is provided in the shielding cover to suck air, so that particles generated through cleaning are sucked. However, in a case where the particles are attached to the substrate chuck again, it may be difficult to suck the attached particles through the exhaust duct provided in the shielding cover. Moreover, in Japanese Patent Laid-Open No. 9-283418, one hole used for sucking with negative pressure is provided in a cleaning member and particles are removed by sucking the particles through the hole. However, even when air is sucked by using negative pressure through the one hole used for sucking with negative pressure, an efficient flow of gas is hard to be generated in a narrow space between the cleaning member and the substrate chuck and it may be difficult to suck particles at positions away from the hole used for sucking with negative pressure.